Chlorinated EPDM with superior stability

ABSTRACT

A chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymer having a chlorine content of from about 0.5 to 14 percent by weight characterized by superior viscosity stability on storage or exposure to elevated temperatures is obtained by chlorinating an ethylene-alpha olefin-nonconjugated diolefin terpolymer wherein said nonconjugated diolefin is an acyclic nonconjugated diolefin characterized in that one olefinic bond is monosubstituted and terminal and the other olefinic bond is trisubstituted. A vulcanizable rubber composition comprising said chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymer and cure active agents is also provided.

FIELD OF INVENTION

This invention relates to a chlorinated ethylene alphaolefin--nonconjugated diolefin terpolymer that exhibits superiorviscosity stability during storage and on exposure to the elevatedtemperatures associated with processing and finishing treatments.

BACKGROUND OF THE INVENTION

Ethylene-propylene-nonconjugated diolefin terpolymers are characterizedby an absence of polymer backbone unsaturation which renders thesematerials extremely resistant to oxidation and ozone. Rubber compoundershave attempted to use these low unsaturationethylene-propylene-nonconjugated diolefin terpolymers in compositionswith highly unsaturated elastomeric materials such as natural rubber,styrene-butadiene rubber, polybutadiene rubber andacrylonitrile-butadiene rubber in order that the terpolymers' oxidationand ozone resistance may be imparted to the highly unsaturated rubbers.However their efforts have not been successful due to the fact that theterpolymers will not compatibly cocure with highly unsaturated naturalrubbers or diene rubbers in blends such as those that are desirably madein the preparation of stocks for passenger car tires, truck tires,aeroplane tires and heavy duty off-the-road tires.

A technique by which the cure compatibility of butyl rubber with naturalrubber and styrene-butadiene rubber has been greatly improved has beenby the halogenation of butyl rubber. Although theethylene-propylene-nonconjugated diolefin terpolymers that are presentlycommercially available are quite different in structure when comparedwith butyl rubber, it has also been found that halogenation of theseterpolymers likewise results in a marked improvement in their curecompatibility with the highly unsaturated rubbers. Unfortunately, thehalogenated ethylene-propylene-nonconjugated diolefin terpolymers inwhich the nonconjugated diolefin is a monomer such as dicyclopentadiene,5-ethylidene-2-norbornene, 5-vinyl-2-norbornene or 1,4-hexadiene arefound to have poor stability as evidenced by undesirable increases inviscosity during storage or when exposed to elevated temperaturesassociated with processing or finishing treatments. In addition, knownethylene-propylene-nonconjugated diolefin terpolymer halogenationprocesses frequently cause an undesirable increase in gel content whichseriously detracts from the processability of the material. Thus thereis a recognized need in the rubber industry for a halogenatedethylene-propylene-nonconjugated diolefin terpolymer that exhibits astability on storage and exposure to elevated temperatures superior tothat shown by halogenated ethylene propylene-nonconjugated diolefinterpolymers which have been previously synthesized.

DESCRIPTION OF PRIOR ART

U.S. Pat. No. 3,524,826 (Kresge et al) discloses that a terpolymer ofethylene, a C₃ to C₈ alpha olefin and a C₅ to C₁₄ nonconjugated diolefincan be reacted with elemental bromine in solution at a temperaturebetween 0° C. and 35° C. to give an additively brominated terpolymercontaining between 1 percent and 10 percent by weight bromine.

Canadian Patent No. 857,383 (Morrisey) discloses that a terpolymer ofethylene, an alpha olefin and a nonconjugated diolefin which ispreferably 1,4-hexadiene, octadecadiene or dicyclopentadiene may behalogenated with molecular halogen or organic halogen-containingmaterials at a temperature between 85° C. and 100° C. in the presence ofultraviolet radiation to afford a halogenated terpolymer comprisingbetween 1 percent and 10 percent by weight halogen.

U.S. Pat. No. 3,896,095 (Morrisey) discloses that an ethylene-propylenepolyene terpolymer wherein said polyene is a member of the groupconsisting of the 5-alkylidene-2-norbornenes, the alkenyl-2-norbornenesand the 5-alkadienyl-2-norbornenes may be uniformly halogenated in crumbform in a water slurry, thereby obviating the need to use organicsolvents and the attendant demand for recovery thereof. The halogenatedterpolymer thus prepared comprises 3 to 6 weight percent halogen,preferably chlorine.

U.S. Pat. No. 3,956,247 (Landi et al) discloses that the solutionhalogenation of an elastomeric terpolymer of ethylene, an alpha olefinand a nonconjugated diene, preferably 5-ethylidene-2-norbornene in thepresence of an epoxy compound such as epoxidized soyabean oil with orwithout a polyalkylene ether glycol yields a halogenated ethylene-alphaolefin--nonconjugated diolefin with excellent viscosity stability andlimited gel content.

SUMMARY OF THE INVENTION

It is an objective of this invention to provide a chlorinatedethylene-alpha olefin--nonconjugated diolefin terpolymer that exhibitssuperior viscosity stability during storage and upon exposure toelevated temperatures associated with processing and finishingtreatments. The nonconjugated diolefin of the base ethylene--alphaolefin--nonconjugated diolefin terpolymer prior to chlorination is anacyclic nonconjugated diolefin with specific structural characteristics.

It is a further objective of this invention to provide a vulcanizablecomposition of said chlorinated ethylene-alpha olefin--nonconjugateddiolefin terpolymer.

Thus in accordance with the present invention there is provided achlorinated ethylene-alpha olefin--nonconjugated diolefin terpolymercharacterized by superior viscosity stability on storage or exposure toelevated temperatures having a chlorine content of from about 0.5 to 14percent by weight based on the weight of said chlorinated terpolymerwherein the base ethylene-alpha olefin--nonconjugated diolefinterpolymer comprises:

(i) about 40 to 80 mol percent ethylene,

(ii) about 20 to 60 mol percent of a C₃ to C₈ alpha olefin, and

(iii) about 0.5 to 10 mol percent of a C₇ to C₁₆ nonconjugated diolefincharacterized in that it is an acyclic nonconjugated diolefin whereinone olefinic bond is monosubstituted and terminal and the other olefinicbond is trisubstituted.

In another aspect, our invention provides a vulcanizable rubbercomposition comprising:

(A) a chlorinated ethylene-alpha olefin--nonconjugated diolefinterpolymer having a chlorine content of from about 0.5 to 14 percent byweight of said chlorinated terpolymer wherein the base ethylene-alphaolefin--nonconjugated diolefin terpolymer comprises:

(i) about 40 to 80 mol percent ethylene,

(ii) about 20 to 60 mol percent of a C₃ to C₈ alpha olefin, and

(iii) about 0.5 to 10 mol percent of a C₇ to C₁₆ nonconjugated diolefincharacterized in that it is an acyclic nonconjugated diolefin whereinone olefinic bond is monosubstituted and terminal and the other olefinicbond is trisubstituted, and

(B) cure active agents.

DETAILED DESCRIPTION OF THE INVENTION

Now, in accordance with the present invention, it has been found thatthe chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymersdescribed herein exhibit superior viscosity stability on storage and onexposure to the elevated temperatures encountered during processing andfinishing treatments.

The preparation of the chlorinated ethylene-alpha olefin-nonconjugateddiolefin terpolymers of the present invention is accomplished by thehalogenation of base ethylene-alpha olefin-nonconjugated diolefinterpolymers. The terpolymers useful in the formation of the products ofthe present invention contain from about 40 to about 80 mol percent ofethylene, from about 20 to about 60 mol percent of a C₃ to C₈alpha-olefin and from about 0.5 to about 10 mol percent of a C₇ to C₁₆nonconjugated diolefin. A preferred ethylene-alpha olefin-nonconjugateddiolefin terpolymer is characterized in that it contains from about 45to about 75 mol percent of ethylene, from about 30 to 55 mol percent ofsaid alpha olefin and from about 1 to about 6 mol percent of saidnonconjugated diolefin and has a number average molecular weight between50,000 and 250,000. Suitable C₃ to C₈ alpha olefins include propylene,1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene, propylene and1-butene being especially preferred. A most important feature of thispresent invention is that the C₇ to C₁₆ nonconjugated diolefin of thebase ethylene-alpha olefin-nonconjugated diolefin terpolymer to bechlorinated, be an acyclic nonconjugated diolefin wherein one olefinicbond is monosubstituted and terminal and the other olefinic bond istrisubstituted. When an ethylene-alpha olefin-nonconjugated diolefinterpolymer in which the diolefin component does not have this particularstructure is chlorinated, the resultant chlorinated ethylene-alphaolefin - nonconjugated diolefin terpolymer does not exhibit the superiorviscosity stability on storage and exposure to elevated temperaturesthat is displayed by the chlorinated ethylene-alphaolefin--nonconjugated diolefin terpolymers of the present invention.Representative nonlimiting examples of suitable nonconjugated diolefinsthat may be used as the third monomer in the terpolymer include3,7-dimethyl-1,6-octadiene, 7-methyl-1,6-octadiene,5,7-dimethyl-1,6-octadiene, 6-methyl-1,5-heptadiene and5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene and7-methyl-1,6-octadiene being especially preferred.

The above described terpolymers are prepared employing techniques wellknown to those skilled in the art. For example, the terpolymers may beproduced by copolymerizing ethylene, an alpha olefin having 3 to 8carbon atoms and a C₇ to C₁₆ acyclic nonconjugated diolefin wherein oneolefinic bond is monosubstituted and terminal and the other olefinicbond is trisubstituted in a reaction medium in the presence of a Zieglercatalyst, comprising, for example, a soluble vanadium compound and anorganoaluminum compound while supplying hydrogen gas, diethyl zinc orthe like as a molecular weight controlling agent. An aliphatichydrocarbon such as hexane, heptane or octane, an alicyclic hydrocarbonsuch as cyclohexane, an aromatic hydrocarbon such as toluene or xyleneand a halogenated hydrocarbon such as chlorobenzene, carbontetrachloride, tetrachloroethylene, methylene dichloride, ordichloroethane may be used as the reaction medium either singly or inadmixture. Alternatively the terpolmyers may be produced in a reactionmedium comprising said alpha olefin having 3 to 8 carbon atoms and oneof the aforesaid hydrocarbons. Examples of the soluble vanadium compoundinclude vanadium tetrachloride, vanadium triacetylacetonate, vanadiumtrialkoxides and halogenated vanadium alkoxides which may be used eithersingly or as a mixture. Examples of the organoaluminum compound includetriethyl aluminum, diethyl aluminum chloride, and ethyl aluminumsesquichloride which may be used singly or as a mixture.

The base terpolymers used in the present invention may also be producedby copolymerizing ethylene, an alpha olefin having 3 to 8 carbon atomsand the alicyclic nonconjugated diolefin with the specific structuralcharacteristics as hereinbefore described in a reaction medium in thepresence of a soluble chiral or nonchiral metallocene catalyst and amethyl aluminoxane cocatalyst at a temperature between -60° C. and 110°C. An alicyclic hydrocarbon such as cyclohexane or an aromatichydrocarbon such as toluene or xylene may be used as the reaction mediumeither singly or in admixture. Examples of the chiral metallocenecatalyst include compounds of the formula ##STR1## where M is a groupIVb metal selected from titanium, hafnium and zirconium, X₁ and X₂ maybe the same or different and are selected from bromine, chlorine andmethyl, L₁ and L₂ are the same or different and each is acyclopentadienyl ligand, and R¹ is a C₁₋₂₀ hydrocarbon which is bondedto said L₁ and said L₂. Examples of the nonchiral metallocene catalystinclude compounds of the formula ##STR2## where M is a group IV b metalselected from titanium, hafnium and zirconium, X₁ and X₂ may be the sameor different and are selected from bromine, chlorine and methyl, L₁ andL₂ are the same or different and each is a cyclopentadienyl type ligand.The methyl aluminoxane cocatalyst used in conjunction with the chiral ornonchiral metallocene catalyst is prepared by carefully reactingtrimethyl aluminum with aluminum sulphate hexadecahydrate in a solutionof toluene.

According to the present invention, the herein before describedterpolymers are chlorinated, using methods well known in the art, toyield a terpolymer containing from about 0.5 to 14 percent by weightchlorine, preferably about 2 to 7 percent by weight chlorine, based onthe weight of said chlorinated terpolymer.

The chlorinating agent used may be molecular chlorine or it may be anorganic chlorine compound of which representative nonlimiting examplesinclude N-chloro succinimide, 1,3-dichloro-5,5-dimethylhydantoin andN-chloro-N-cyclohexylbenzene sulphonamide; 1,3-dichloro-5,5-dimethylhydantoin being preferred.

The preferred method for preparing the chlorinated ethylene-alphaolefin-nonconjugated diolefin terpolymers of the present inventioninvolves dissolution of the base terpolymer in a suitable inert organicsolvent which may be a saturated aliphatic hydrocarbon such as hexane orheptane; an aromatic hydrocarbon such as toluene or mixed xylenes; analicyclic hydrocarbon such as cyclohexane or methyl cyclohexane; orhalogenated derivatives of the above hydrocarbons such as chloroform,carbon tetrachloride and the like to afford a 3 to 15 weight percentsolution. There may also be dispersed about 10 percent by volume ofwater in this polymer solution to facilitate the removal of the hydrogenchloride generated during the chlorination of the base terpolymer. Tothis polymer solution there is added with agitation molecular chlorine,preferably dissolved in a suitable solvent such as chloroform or carbontetrachloride, in a quantity sufficient to achieve the desired level ofchlorination. Preferably the reaction is carried out in the absence ornear absence of light. The chlorination reaction can be conducted at atemperature ranging from about 0° C. to 50° C., preferably from about15° C. to 35° C. After a reaction time of about 3 minutes to 15 minutes,a solution of an alkaline reagent, preferably either an aqueous sodiumhydroxide solution of about 5 weight percent or an aqueous potassiumhydroxide solution of about 5 weight percent, is added to the polymersolution to neutralize the excess chlorine and hydrogen chloride formedduring the chlorination reaction. After about 10 minutes the polymersolution is washed with water to remove the inorganic salts and thensuitable stabilizers and antioxidants are added. Examples of suitablestabilizers include calcium stearate and epoxidized soyabean oil,preferably used in the amount of about 0.05 to 5 parts by weight perhundred parts by weight of said chlorinated terpolymer. Suitableantioxidants include sterically hinered phenols, preferably used in theamount of about 0.05 to 2 parts by weight per hundred parts by weight ofsaid chlorinated terpolymer. Recovery of said chlorinated terpolymer isachieved by conventional techniques used to recover rubbery polymersincluding (i) contacting the polymer solution with steam therebyflashing off the solvent (ii) passing the wet polymer over a screen orfilter in order to recover the polymer and (iii) passing the polymerthrough a tunnel dryer or extruder. The chlorinated terpolymer may alsobe recovered by coagulation with an excess of an organic liquid in whichthe chlorinated polymer is sparingly soluble, examples of such a liquidbeing methanol, isopropanol or acetone.

Chlorination of the base ethylene-alpha olefin-nonconjugated diolefinterpolymer may also be accomplished by reaction of said terpolymer withan organic chlorinating reagent. A quantity of the organic chlorinatingreagent sufficient to achieve the desired level of chlorination is addedto a solution of said base terpolymer in an appropriate inert organicsolvent, preferably dichloromethane, chloroform or carbon tetrachloride.The reaction may be carried out at a temperature of about 15° C. toabout 30° C. or, alternatively, in the presence of a free radicalinitiator such as an organic peroxide, at a more elevated temperature ofabout 50° C. to 90° C. The reaction period may extend from about onehour to about 24 hours, preferably from about one hour to about 16 hourswhen the reaction is carried out in the absence of a free radicalinitiator and from about one hour to about 4 hours when the reaction iscarried out in the presence of a free radical initiator. The polymersolution is decanted from any insoluble by-products that settle out.Stabilization and isolation of the chlorinated terpolymer thus producedis accomplished as hereinbefore described.

Chlorination by either molecular chlorine or an organic chlorinecompound of the base ethylene-alpha olefin-nonconjugated diolefinterpolymers of the present invention is believed to occur by apredominantly substitution mechanism wherein one chlorine atom issubstituted for a hydrogen atom in the position allylic to the doublebond thereby giving rise to chlorinated ethylene-alphaolefin-nonconjugated diolefin terpolymers with allylic chloridestructures analogous to the structures of the allylic chlorides formedupon chlorination of butyl rubber. While not wishing to be bound by anytheories it is believed that it is the similarity of the structures ofthe allylic chlorides in the chlorinated ethylene alphaolefin-nonconjugated diolefin terpolymers of the present invention tothe structures of the allylic chlorides in chlorobutyl rubber thataccounts for the superior stability on storage or exposure to elevatedtemperatures exhibited by said chlorinated ethylene-alphaolefin-nonconjugated diolefin terpolymers.

The chlorine containing terpolymers of the present invention, preparedby chlorination of the base ethylene-alpha olefin-nonconjugated diolefinterpolymers as hereinbefore described can be cured with a variety ofcuring systems to afford vulcanizates that possess a desirable balanceof physical properties. The vulcanizing agent may, for example, be ametal salt, a sulphur-containing compound, an organic peroxide or analkyl phenol-formaldehyde resin or a combination of these. A typicalcuring system comprises: (i) a metal oxide, (ii) elemental sulphur and(iii) at least one sulphur based accelerator. The use of metal oxides asa component in the curing system is well known in the art. A suitablemetal oxide is zinc oxide which is used in amounts of from about 1 to10, preferably from about 2 to about 5, parts by weight per 100 parts byweight chlorinated terpolymer. Elemental sulphur, comprising component(ii) of said curing system is used in amounts of from about 0.2 to about2 parts by weight per 100 parts by weight chlorinated terpolymer.Suitable sulphur based accelerators (component (iii) of said curingsystem) are used in amounts of from about 0.5 to about 3 parts by weightper 100 parts by weight chlorinated terpolymer and may be selected fromthe thiuram sulphides such as tetramethyl thiuram disulhpide (TMTD), thethiocarbamates such as zinc dimethyl dithiocarbamate (ZDC) and thethiazyl and benzothiazyl compounds such as mercaptobenzothiazyldisulphide (MBTS). Preferably the sulphur based accelerator ismercaptobenzothiazyl disulphide.

Another typical curing system comprises: (i) an organic peroxide and(ii) a peroxide activator. Representative organic peroxides includedi-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexaneand dicumyl peroxide (DiCup 40 [tradename]) and are used in the amountof from about 0.5 to 5, preferably from about 1 to 3 parts by weight per100 parts by weight chlorinated terpolymer. Examples of the peroxideactivator used in combination with the organic peroxide include quinonedioxime compounds such as p-quinonedioxime, methacrylate compounds suchas polyethylene glycol dimethacrylate and maleimide compounds such asN,N'-m-phenylene dimaleimide (HVA-2 [tradename]). The peroxide activatoris used in an amount of from about 0.5 to 5, preferably from about 1 to3 parts by weight per 100 parts by weight chlorinated terpolymer.

The chlorinated ethylene-alpha olefin--nonconjugated diolefinterpolymers of the present invention may also be vulcanized using thecure system comprising (i) a metal oxide and (ii) an alkyl phenolformaldehyde resin. A suitable metal oxide is zinc oxide which is usedin amounts of from about 1 to 10, preferably from about 2 to about 5,parts by weight per 100 parts by weight chlorinated terpolymer. Thesecond component of the cure system the alkyl phenol formaldehyde resin,a representative example of which is the commercially available SP-1045(tradename) is used in the amount of from about 0.5 to 5 parts,preferably about 1 to 4 parts by weight per 100 parts by weightchlorinated terpolymer.

The use of reinforcing agents such as various carbon blacks and finelydivided silica to impart improved strength properties to the finalvulcanizate is well known in the art. Suitable carbon blacks forpractising this invention are the well known furnace and channel,preferably furnace blacks and are used in the amounts of from about 30to about 100, preferably from about 50 to about 80, parts by weight per100 parts by weight chlorinated terpolymer.

Hydrocarbon extender oil, antioxidants, antiozonants, processing aidsand tackifiers may also be added in the usual way and in the normalamounts for compounding ethylene-alpha olefin-nonconjugateddiolefin-type rubbery polymers.

The procedure of mixing the various components of the vulcanizablerubber compositions of this invention is not specifically restricted.Generally, it is preferred to carry out the compounding procedure in twostages. In the first stage the polymer may be mixed with theconventional compounding ingredients which may include carbon black,hydrocarbon extender oil, antioxidants, processing aids and tackifiers.In the second stage of the compounding procedure, the cure active agentsare preferably added to the compound described above on a rubbermill orin an internal mixer operated at a temperature normally not in excess ofabout 60° C. The compounds are cured in a conventional manner by heatingfrom about 5 to about 60 minutes at temperatures of from about 150° C.to about 200° C. to form elastomeric vulcanizates which demonstrate adesirable balance of physical properties. By physical properties ismeant hardness, elongation and strength properties which include modulusat 100 percent elongation, modulus at 300 percent elongation and tensilestrength at rupture. Accordingly, said vulcanizates are suitable for usein articles where conventional chlorinatedethylene-propylene-nonconjugated diolefin terpolymers based on thenonconjugated diolefins 2-ethylidene-5-norbornene, dicyclopentadiene and1,4-hexadiene are presently used.

The following examples illustrate the present invention and are notintended to limit the scope thereof. All parts are parts by weightunless otherwise specified.

EXAMPLE 1

An ethylene-propylene-7-methyl-l,6-octadiene terpolymer rubber wasprepared by polymerizing ethylene, propylene and 7-methyl-1,6-octadienein toluene at -5° C. using the chiral metallocenebis(tetrahydroindenyl)ethane zirconium dichloride and methyl aluminoxanecatalyst system. Characterization of the terpolymer by nuclear magneticresonance (NMR) and infrared (IR) spectroscopy and gel permeationchromatography (GPC) in which the molecular weights were determined aspolystyrene molecular weight equivalents showed that the terpolymerrubber comprised 50 mol percent ethylene, 49 mol percent propylene and1.6 mol percent 7-methyl-1,6-octadiene, had a number average molecularweight (M_(n)) 127,000, a weight average molecular weight (M_(w))348,600 and a polydispersity (M_(w) /M_(n)) of 27.5.

One hundred grams of said terpolymer rubber was dissolved in 1000 ml ofn-hexane. To this cement in a 3-litre glass reactor equipped with astirrer and an inlet valve was added 100 ml of water and the resultantmixture was stirred vigorously for 10 minutes to ensure completedispersion of the water in the cement. The reactor was wrapped withaluminum foil in order to keep it free of ambient light and then 3.1grams of chlorine in about 50 ml of carbon tetrachlorine was added withagitation. After 3 minutes 1.9 grams of sodium hydroxide in about 40 mlof water was added and the reaction mixture was stirred vigorously for afurther 10 minutes in order to ensure complete neutralization of thehydrogen chloride generated during the reaction. The polymer was thencoagulated by pouring the reaction mixture into about 3500 ml ofmethanol. The polymer was washed thoroughly three times with methanol,allowed to drain at room temperature and dried in a vacuum oven forabout 6 hours at ambient temperature. he polymer, together with 0.2grams Irganox 1076(tradename), 0.5 grams calcium stearate and 0.1 gramParaplex G-62(tradename), were dissolved in 1000 ml of n-hexane. Thepolymer was then coagulated by pouring the polymer solution into about3000 ml of acetone. The polymer was allowed to drain at roomtemperature, dried in a vacuum oven for about 16 hours at ambienttemperature and finally on a two-roll mill at approximately 50° C. Thechlorinated terpolymer thus obtained contained 1.8 weight percentchlorine and had a Mooney viscosity (ML 1+4 at 100° C.) of 47.

The long term stability of the chlorinated terpolymer was evaluated bycarrying out an accelerated aging study whereby 35 gram samples of thepolymer, wrapped in polyethylene film, were aged in a hot air oven at80° C. for 2 days, 7 days and 20 days and the Mooney viscosities of therespective samples then determined. The results, which are given inTable I, show that there was essentially no change in the Mooneyviscosity over the time period, thereby demonstrating the inherentstability of the chlorinated terpolymer.

EXAMPLE 2

This example is outside the invention and is included for purposes ofcomparison.

The procedure of Example 1 was essentially followed except that onehundred grams of an ethylene-propylene-5-ethylidene-2-norborneneterpolymer designated EPDM 345, sold by Polysar Limited, Sarnia,Ontario, Canada was used. This polymer has an ethylene:propylene weightratio of 74:26, and contains 4.3 weight percent, based on the EPDM, of5-ethylidene 2-norbornene and has an M_(n) 110,000, M_(w) 262,000, andM_(w) /M_(n) 2 4. For the chlorination reaction 2.55 grams of chlorinein about 40 ml of carbon tetrachloride was utilized and for neutralizingthe hydrogen chloride formed in said reaction, 1.6 grams of sodiumhydroxide in about 30 ml of water was used. The chlorinated terpolymerthus obtained contained 1.1 weight percent chlorine and had a Mooneyviscosity (ML 1+4 at 100° C.) of 45.

An accelerated aging study of the polymer, the results of which aregiven in Table I, revealed that there was a continual increase in theMooney viscosity during the twenty days.

EXAMPLE 3

The procedure of Example 1 was essentially followed with exception thatthe base ethylene-propylene-7-methyl-1,6-octadiene terpolymer rubbercomprised 56 mol percent ethylene, 38 mol percent propylene and 6 molpercent 7-methyl-1,6-octadiene, had an M_(n) 111,000, M_(w) 303,000 andM_(w) /M_(n) 2.7. Chlorination of said terpolymer was accomplished using10.9 grams of chlorine in about 160 ml of carbon tetrachloride andneutralization of the hydrogen chloride formed in said reaction wascarried out using 6.7 grams of sodium hydroxide in about 130 ml ofwater. The chlorinated terpolymer thus obtained contained 5.3 weightpercent chlorine and had a Mooney viscosity (ML 1+4 at 100° C.) of 27.

An accelerated aging study of said chlorinated terpolymer, the resultsof which are given in Table I, revealed that there was essentially nochange in the Mooney viscosity over the twenty days.

EXAMPLE 4

This example is outside the invention and is intended for purposes ofcomparison.

The procedure of Example 1 was essentially followed except that onehundred grams of an ethylene-propylene-5-ethylidene-2-norborneneterpolymer designated EPDM 585, sold by Polysar Limited, Sarnia,Ontario, Canada was used. This polymer has an ethylene:propylene weightratio of 62:38, and contains 10.9 weight percent, based on the EPDM, of5-ethylidene-2-norbornene and has an M_(n) 119,000, M_(w) 312,000 andM_(w) /M_(n) 2.6.

For the chlorination reaction 6.4 grams of chlorine in about 100 ml ofcarbon tetrachlorine was utilized and neutralization of the hydrogenchloride formed in said reaction was accomplished using 4.0 grams ofsodium hydroxide in about 80 ml of water. The chlorinated terpolymerthus obtained contained 1.5 weight percent chlorine and had a Mooneyviscosity (ML 1+4 at 100° C.) of 81.

An accelerated aging study of said chlorinated terpolymer, the resultsof which are given in Table I, revealed that there was a verysubstantial increase in the Mooney viscosity within 2 days and thatwithin 7 days said chlorinated terpolymer had become crosslinked to suchan extent that it was no longer possible to obtain a value for theMooney viscosity.

                  TABLE I                                                         ______________________________________                                                   Examples                                                                               2               4                                         (ML 1 + 4 at 100° C.)                                                               1      (comparative)                                                                            3    (comparative)                             ______________________________________                                        Unaged       47     45         27    81                                       Aged 2 days at 80° C.                                                               47     49         30.5 200                                       Aged 7 days at 80° C.                                                               48     54         31   crumb                                     Aged 20 days at 80° C.                                                              49.5   61         33.3 crumb                                     ______________________________________                                    

A comparison of the results of the accelerated aging studies of the twochlorinated ethylene-propylene-7- methyl-1,6-octadiene terpolymers withthose of the accelerated aging studies of the two chlorinatedethylene-propylene-5-ethylidene-2-norbornene terpolymers under identicalconditions clearly demonstrates the importance of the structure of thenonconjugated diolefin in the base ethylene-propylene-nonconjugateddiolefin terpolymer to the eventual long term stability of thechlorinated terpolymer. It is only when the nonconjugated diolefin inthe base terpolymer is an acyclic nonconjugated diolefin wherein oneolefinic bond is monosubstituted and terminal and the other olefinicbond is trisubstituted that a chlorinatedethylene-propylene-nonconjugated diolefin with superior viscositystability can be obtained by chlorination of said base terpolymer.

EXAMPLE 5

Five elastomeric formulations according to the present invention, andconsisting of a chlorinated ethylene-propylene-7-methyl-1,6-octadieneterpolymer as the only elastomer, were prepared, cured and tested. Forcomparison purposes formulations containing chlorinatedethylene-propylene-5-ethylidene-2-norborene terpolymer were prepared,cured and similarly tested.

In the formulations according to the invention, the terpolymer used wasan chlorinated ethylene-propylene-7-methyl-1,6-octadiene terpolymerhaving a chlorine content of 1.2 weight percent based on the weight ofsaid chlorinated terpolymer, wherein the baseethylene-propylene-7-methyl-1,6-octadiene terpolymer comprised 59 molpercent ethylene, 42 mol percent propylene and one mol percent7-methyl-1,6-octadiene. The chlorinated terpolymer had M_(n) 100,000,M_(w) 223,000 and M_(w) /M_(n) 2.2.

In the comparison formulations, the terpolymer used was a freshlyprepared chlorinated ethylene-propylene-5-ethylidene-2-norborneneterpolymer having a chlorine content of 1.1 weight percent based on theweight of said chlorinated terpolymer, wherein the baseethylene-propylene-5-ethylidene-2-norbornene terpolymer designated EPDM345 and sold by Polysar Limited, Sarnia, Ontario, Canada has anethylene:propylene weight ratio of 74:26 and contains 4.3 weight percentbased on the EPDM, of 5-ethylidene-2-norbornene. The chlorinatedterpolymer had M_(n) 110,000, M_(w) 262,000, and M_(w) /M_(n) 2.4.

The ten chlorinated ethylene-propylene-nonconjugated diolefin terpolymercompounds were prepared according to the general recipe shown in TableII. The materials used were carbon black, an N-660 type commercialproduct and paraffinic oil, commercial product sold as Sunpar 2280.

Zinc oxide (vulcanization agent), sulphur (vulcanization agent), TMTD(tetramethylthiurarm disulphide:accelerator), MBTS (mercaptobenzothiazyldisulphide:accelerator), DiCup 40C (dicumyl peroxide on precipitatedcalcium carbonate:vulcanization agent), HVA-2 (N-N'-m-phenylenedimaleimide:accelerator) and SP-1045 (alkyl phenol formaldehyderesin:vulcanization agent) were commercially available materials.Compounding was done by mixing all the components with the exception ofthe cure active agents on a two roll rubbermill. The temperature of themill at commencement of the mixing procedure was ambient temperature andthe mixing cycle was completed in about 10 to 15 minutes. Compoundingwas completed by adding the remaining ingredients on the two rollrubbermill at ambient temperature. The compounded stocks were formedinto sheets and vulcanized in a Preco press at 166° C. under a pressureof 35,000 psi for times varying from about 5 minutes to about 60minutes; the cure time being dependent upon the particular cure systemused.

Tensile strength, modulus at 100 percent and 300 percent elongation andultimate elongation to break were determined according to ASTM-D 412-80.Hardness was determined using a Type A shore durometer according to ASTMD 2240-81. The test results on the vulcanizates are provided in TableIII.

The test results indicate that vulcanizates derived from rubbercompositions of this invention possess the necessary balance of physicalproperties which renders them useful as replacements for the controlformulations.

                                      TABLE II                                    __________________________________________________________________________            Sample No.                                                                    1  2    3    4   5    6  7    8    9   10                             __________________________________________________________________________    Chlorinated                                                                           100                                                                              100  100  100 100  -- --   --   --  --                             exptl. polymer                                                                Chlorinated                                                                           -- --   --   --  --   100                                                                              100  100  100 100                            EPDM 345                                                                      Stearic acid                                                                           1  1    1   --   1    1  1    1   --   1                             Carbon black                                                                          50 50   50   50  50   50 50   50   50  50                             Sunpar 2280                                                                           10 10   10   --  10   10 10   10   --  10                             Zinc oxide                                                                             5  5    5        5    5  5    5        5                             TMTD    --    0.25                                                                            --   --  --   --    0.25                                                                            --   --  --                             MBTS    -- --      1.25                                                                            --  --   -- --       1.25                                                                           --  --                             Sulphur -- --     0.5                                                                              --  --   -- --     0.5                                                                              --  --                             DiCup 40C                                                                             -- --   --     1.5                                                                             --   -- --   --     1.5                                                                             --                             HVA-2   -- --   --     1.5                                                                             --   -- --   --     1.5                                                                             --                             SP - 1045                                                                             -- --   --   --     1.75                                                                            -- --   --   --     1.75                        __________________________________________________________________________

                                      TABLE III                                   __________________________________________________________________________             Sample No.                                                                    1   2   3   4   5   6   7   8   9   10                               __________________________________________________________________________    VULCANIZATE                                                                   PROPERTY                                                                      Hardness,                                                                              60  58  61  66  61  54  60  57  52  56                               Shore A                                                                       100% Modulus                                                                           1.7 2.4 1.7 2.3 1.9 1   1.2 1.4 1.1 1                                MPa                                                                           300% Modulus                                                                           6.8 10  6.4 --  7.9 2.4 3.9 6.9 2.8 2.9                              MPa                                                                           Tensile  9.3 11.5                                                                              13.7                                                                              5.5 10.7                                                                              13.1                                                                              10.8                                                                              20.8                                                                              11.2                                                                              12.1                             Strength                                                                      MPa                                                                           Elongation %                                                                           390 330 535 165 385 835 545 655 785 710                              __________________________________________________________________________

What is claimed is:
 1. A chlorinated ethylene-alpha olefin-nonconjugated diolefin terpolymer characterized by superior stability on storage or exposure to elevated temperatures having a chlorine content of from about 0.5 to 14 percent by weight based on the weight of said chlorinated terpolymer wherein the base ethylene-alpha olefin-nonconjugated diolefin terpolymer comprises:(i) about 40 to 80 mol percent ethylene, (ii) about 20 to 60 mol percent of a C₃ to C₈ alpha olefin, and (iii) about 0.5 to 10 mol percent of a C₇ to C₁₆ nonconjugated diolefin characterized in that it is an acyclic nonconjugated diolefin wherein one olefinic bond is monosubstituted and terminal and the other olefinic bond is trisubstituted.
 2. The chlorinated terpolymer of claim 1 wherein said C₃ to C₈ alpha olefin is selected from the group consisting of propylene and 1-butene.
 3. The chlorinated terpolymer of claim 2 wherein said C₃ to C₈ alpha olefin is propylene.
 4. The chlorinated terpolymer of claim 3 wherein said nonconjugated diolefin is selected from the group consisting of 3,7-dimethyl-1,6-octadiene, 5,7-dimethyl-1,6-octadiene,7-methyl- 6-octadiene,5-methyl-l,4hexadiene and 6-methyl-1,5-heptadiene.
 5. The chlorinated terpolymer of claim 4 wherein said nonconjugated diolefin is selected from the group consisting of 3,7-dimethyl-1,6-octadiene and 7-methyl-1,6-octadiene.
 6. The chlorinated terpolymer of claim 1 having a chlorine content of from about 2 to about 7 percent by weight based on the weight of said chlorinated terpolymer wherein the base ethylene-alpha olefin-nonconjugated diolefin terpolymer comprises:(i) about 40 to 80 mol percent ethylene, (ii) about 20 to 60 mol percent of a C₃ to C₈ alpha olefin, and (iii) about 1 to 6 mol percent of a C₇ to C₁₆ nonconjugated diolefin characterized in that it is an acyclic nonconjugated diolefin wherein one olefinic bond is monosubstituted and terminal and the other olefinic bond is trisubstituted.
 7. The chlorinated terpolymer of claim 6 wherein said C₃ to C₈ alpha olefin is selected from the group consisting of propylene and 1-butene.
 8. The chlorinated terpolymer of claim 7 wherein said C₃ to C₈ alpha olefin is propylene.
 9. The chlorinated terpolymer of claim 7 wherein said nonconjugated diolefin is selected from the group consisting of 3,7-dimethyl-1,6-octadiene,5,7-dimethyl -1,6-octadiene,7-methyl-1,6-octadiene,5-methyl-1,4-hexadiene and 6-methyl-1,5-heptadiene.
 10. The chlorinated terpolymer of claim 9 wherein said nonconjugated diolefin is selected from the group consisting of 3,7-dimethyl-1,6-octadiene and 7-methyl-1,6-octadiene.
 11. The chlorinated terpolymer of claim 10 wherein said base ethylene-propylene-nonconjugated diolefin terpolymer comprises:(i) about 45 to 75 mol percent ethylene, (ii) about 30 to 55 mol percent propylene, and (iii) about 1 to 6 mol percent of a nonconjugated diolefin selected from the group consisting of 3,7-dimethyl-1,6-octadiene and 7-methyl-1,6-octadiene. 